cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A233767 Prime(n), where n is such that (Sum_{i=1..n} prime(i)^19) / n is an integer.

Original entry on oeis.org

2, 97, 3203, 5059, 6469, 8081, 35051, 39719, 42209, 109049, 154591, 523297, 6621827, 20059771, 258196441, 731584957, 1427109029, 1899496631, 8428550519, 50790885203, 7475902096387, 22626378502139, 38855796912367, 162082298018497, 589085299527401, 4271778258271487
Offset: 1

Views

Author

Robert Price, Dec 15 2013

Keywords

Comments

a(26) > 661876608760109. - Bruce Garner, Jun 30 2021
a(27) > 18205684894350047. - Paul W. Dyson, Dec 31 2024

Examples

			97 is a term, because 97 is the 25th prime and the sum of the first 25 primes^19 = 71486619210134792705255313675343157050 when divided by 25 equals 2859464768405391708210212547013726282 which is an integer.
		

Crossrefs

Cf. A085450 (smallest m > 1 such that m divides Sum_{k=1..m} prime(k)^n).

Programs

  • Mathematica
    t = {}; sm = 0; Do[sm = sm + Prime[n]^19; If[Mod[sm, n] == 0, AppendTo[t, Prime[n]]], {n, 100000}]; t (* Derived from A217599 *)
  • PARI
    is(n)=if(!isprime(n),return(0)); my(t=primepi(n),s); forprime(p=2,n,s+=Mod(p,t)^19); s==0 \\ Charles R Greathouse IV, Nov 30 2013
    
  • PARI
    my(S=n=0);forprime(p=1,,(S+=p^19)%n++||print1(p", ")) \\ M. F. Hasler, Dec 01 2013

Formula

a(n) = prime(A131279(n)).

Extensions

a(21) from Karl-Heinz Hofmann, Feb 24 2021
a(22) from Bruce Garner, Mar 01 2021
a(23) from Bruce Garner, Mar 08 2021
a(24) from Bruce Garner, Apr 14 2021
a(25) from Bruce Garner, Jun 30 2021
a(26) from Paul W. Dyson, Jun 27 2023